Hed3 help
 

Hey everyone i was wondering what kind of hubs do HED3 use and the axle size?
here's my problem, i have a pair of hed's and I've converted the front to a bolt on for track an now i only have the rear left. The rear hed3 is a free hub and I'm not quite familiar with them. I was going to buy the hed track axle conversion or i could just buy the a surly fixxer they both look the same. the fixxer is about $80 and the hed one is $120 a big difference!
These are HED3 NOT THE HED3c OR THE SPECIALIZED ONES

So my questions are..
Is a surly fixxer and the hed track axle converter the same?
what kind of hub is on the hed3?